Move most of the launching code into libdotdesktop_standard so that RetiledStart can use it more easily.

[DrewNaylor]

There will be arguments that can be set when calling the launcher code in case it's being run from LaunchDotDesktop, mainly the input box thing. May have to get rid of that if it won't build, or check if it's running on Windows or not.

[DrewNaylor]

What I can do is move most of the code into a cleaning function, then have it return a mostly-cleaned Exec key. Afterward the application using libdotdesktop_standard is responsible for cleaning up any remaining stuff (such as the file browse dialog-related part), just so that the Windows Forms dependency can be removed to prevent issues on Linux and FreeBSD (if .NET is ever officially supported on it and I can figure out how to support it and get around to a build for it).

[DrewNaylor]

Actually, I could have an optional argument that will fully clean the Exec key, removing the %u and %f stuff as an example. Programs using it will then have an option to replace those strings their own way.

[DrewNaylor]

This is mostly done now. See #13 for the latest developments.